Electric motor, particularly a commutator motor sealed to be liquid-tight, for driving an axially flange-mounted hydraulic pump

ABSTRACT

An electric motor and drive housing assembly includes a motor housing having an open end and a drive housing. The motor housing is affixed to the drive housing such that the opening of the motor housing faces the outer surface of the drive housing. A rotor accommodated in the motor housing has a rotor shaft supported in the motor housing and extending through the opening. A commutator is mounted on the rotor shaft in a region of the opening. A shaft bearing is mounted on the rotor shaft in a region of the opening. A brush carrier plate is attached to the motor housing and closes the opening. The brush carrier plate forms an end plate of the motor housing and a liquid-tight seal between the motor housing and the drive housing. Brushes are mounted on the brush carrier plate for cooperation with and shifting movement with respect to the commutator. Further, a centering arrangement is provided in the brush carrier plate for centering the shaft bearing.

BACKGROUND OF THE INVENTION

The invention relates to an electric motor, particularly a commutatormotor sealed to be liquid-tight. The motor has a bowl-shaped motorhousing to which a drive housing is axially flanged. The drive housingaccommodates, for example, a hydraulic pump driven by the electricmotor. The motor further has a brush carrier plate which supportsbrushes shiftable relative to the commutator and which is disposedbetween the end faces of the motor housing and the device housing.Axially flange-mounted hydraulic pump of the type disclosed in thepreamble to claim 1.

An electric motor is already known from EP 0,472,746.A1, in which therotary shaft projects with an eccentric shaft end, which drives theplungers of a flange-mounted hydraulic pump, from the end face of apot-shaped motor housing sealed by an end shield. Moreover, a separatecarrier plate is provided in the end shield for brushes that cooperatein a known way with the commutator provided on the drive. Because of thenumerous individual parts, the assembly expenditure in this knownelectric motor is considerably high.

SUMMARY OF THE INVENTION

It is the object of the invention to further simplify and reduce thecost of an electric motor for driving a hydraulic pump with regard toproduction and assembly expenditures. This object is accomplished by theinvention, according to which, briefly stated, the electric motor anddrive housing assembly includes a motor housing having an open end and adrive housing. The motor housing is affixed to the drive housing suchthat the opening of the motor housing faces the outer surface of thedrive housing. A rotor accommodated in the motor housing has a rotorshaft supported in the motor housing and extending through the opening.A commutator is mounted on the rotor shaft in a region of the opening. Ashaft bearing is mounted on the rotor shaft in a region of the opening.A brush carrier plate is attached to the motor housing and closes theopening. The brush carrier plate forms an end plate of the motor housingand a liquid-tight seal between the motor housing and the drive housing.Brushes are mounted on the brush carrier plate for cooperation with andshifting movement with respect to the commutator. Further, a centeringarrangement is provided in the brush carrier plate for centering theshaft bearings.

The electric motor flange-mounted to the drive housing (pump housing) ofthe hydraulic pump no longer has an end shield that seals the motorhousing to be liquid-tight. According to the invention, the brushcarrier plate assumes the sealing function between the motor housing andthe pump housing. In addition, the brush carrier plate servessimultaneously as a centering element for a bearing secured to the motorshaft. Because of this, a test of the electric motor has already beenperformed in this stage of assembly. Also, the electric motor can besafely transported in this pre-assembled state. The omission of the endshield creates an inexpensive and easy-to-assemble electric motor unitfor a hydraulic pump.

The invention is described in detail below by way of an embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an axial partial section of a commutator motor having aflange-mounted pump housing, and is FIG. 2 is a detail from FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows an electric motor, particularly a sealed, liquid-tightcommutator motor 1, having a pot-shaped (bowl-shaped) motor housing 3whose cylindrical jacket part 4 is provided on the inner side 7 withpermanent magnets 9, 11. A rotary shaft 13 to which a rotor lamina stack15 is secured is disposed in the motor housing, 3 the stack receiving arotor winding 19 connected to a commutator 17. The commutator 17 is incontact connection with brushes 25, 27, which are acted upon by springs21, 23 and are guided in housings 29, 31. These guide housings 29, 31are fixedly connected to a brush carrier plate 33 and are made of, forexample, brass. The motor housing 3 is flange-mounted to an end face 35of a pump housing 37 of a hydraulic pump not shown in detail. A flatsealing element is disposed between the end faces of the motor housing 3and the pump housing 37. The rotary shaft 13 is seated on the one handin, for example, a bearing 39 inside motor housing 3 and on the otherhand in a bearing 41 which is, for example, a roller bearing having anouter ring 43 and an inner ring 45. According to FIG. 1, the bearing 39is a sliding bearing held by a set of clamping braces 89, but within thescope of the invention, this bearing can also comprise a roller bearing.The bearing 39 can also be disposed in pump housing 37 as a furtherbearing for the rotary shaft 13. The roller bearing 41 is a sealedbearing that prevents the penetration of liquids into the bearing, andthus into the motor housing 3.

The rotary shaft 13 protrudes with its extended eccentric end 91 intothe pump housing 37, which drives, for example, a motor vehicleanti-locking system by means of non-illustrated pump plungers, of thehydraulic pump.

According to the invention, the flat sealing element between the endfaces of the motor housing 3 and the pump housing 37 is the brushcarrier plate 33, made of insulating material, for the brushes 25, 27,which cooperate with commutator 17. This brush carrier platesimultaneously serves as a centering element for the bearing 41, whichis fixedly disposed on the rotary shaft 13, and is fixedly connected asa lid to motor housing 3. The pot-shaped motor housing 3 is provided inthe border edge 47 of its cylindrical opening with a stepped fittingsurface 49 for a liquid-tight engagement of the correspondinglyconfigured, disk-shaped brush carrier plate 33, which is provided at itsouter edge with a cylindrical flange part 51. Furthermore, the brushcarrier plate 33, which can be pressed form-fittingly into the openingof the motor housing 3, has at the outer edge 53 of its inside end face55 a plurality of resilient latching hooks 57, whose notches 59 canlatch behind latching edges 61 formed by metal deformations of motorhousing 3. These metal deformations can consist of pushed-throughbundles 63 in the motor housing 3, or partially stamped, flexible tabs.The above features result in simple assembly of the brush carrier plate33 with the motor housing 3, while at the same time a reliable latchingof the brush carrier plate 33 with the motor housing 3 and precisepre-centering of the rotary shaft 13 in the motor housing 3 areeffected. In this way, a preassembled electric motor 1 for a hydraulicpump is obtained that is already fully testable in this stage, and isalso transportable.

According to FIG. 1, at least the bearing 41 is a sealed roller bearingwhose outer ring 43 is seated on the one hand in a centering recess 65in the outer end face 67 of brush carrier plate 33, and on the otherhand in a bearing recess 69 in end face 35 of the gear housing 37, andwhose inner ring 45 is fixedly disposed with a press fit on a bearingsurface 71 of the rotary shaft 13. To reliably prevent the penetrationof liquids, for example oil, into the interior of the motor housing 3from the bearing 41, the centering recess 65 in the end face 67 of thebrush carrier plate 33 has an annular, stepped impression 73 as alabyrinth seal in front of the roller bearing 41. Furthermore, the brushcarrier plate 33 can be provided at the outer edge 75 on its end face 67the facing pump housing 37 with a sealing lip 77. This reliably preventsthe penetration of liquids into motor housing 3 from the outside. Ifnecessary, the end face 67 of the brush carrier plate 33 can have moreannular protrusion 79, 81 as sealing rings disposed concentrically tothe centering recess 65 (see FIG. 2). The sealing lip 77 and/or thesealing rings 79, 81 are integral with the brush carrier plate 33. Withthis measure, a reliable sealing effect against the penetration ofliquids into the motor housing 3 is achieved without additionalcomponents. It is possible to secure the motor housing 3 to the pumphousing 37 in that the motor housing 3 has a flange part 83 that hasthroughgoing openings for screws, not shown, and is outwardly-orientedby 90°, in the opening of the cylindrical jacket part. In a preciseembodiment of the flange part 83 and the end face 35 of the pump housing37, a sealing effect of this type against the penetration of liquidsinto pump housing 37 or motor housing 3 is already achieved that renderssuperfluous sealing lip 77 on brush carrier plate 33.

The bearing 39 for the rotary shaft 13 according to FIG. 1 is disposedin a correspondingly deep-drawn profiling 85 in the floor part 87 of thepot-shaped motor housing 3. The motor housing 3, including the profiling85, is produced in one work cycle, producing a less expensive andeasy-to-assemble electric motor. The electric motor 1 of the inventionis therefore well-suited for automatic production, with the omission ofthe end shield of the motors known up to now.

I claim:
 1. An electric motor and drive housing assembly, comprising(a)a motor housing having an open end; (b) a drive housing having an outersurface; said motor housing being affixed to said drive housing suchthat said opening of said motor housing faces said outer surface of saiddrive housing; said drive housing having a bearing recess; (c) a rotoraccommodated in said motor housing; said rotor having a rotor shaftsupported in said motor housing and extending through said opening; (d)a commutator mounted on said rotor shaft in a region of said opening;(e) a brush carrier plate made of an insulating material and beingattached directly to said motor housing and closing said opening; saidbrush carrier plate having(1) an end face being in engagement with saidouter surface of said drive housing; said brush carrier plate forming anend plate of said motor housing and a liquid-tight seal between saidmotor housing and said drive housing; and (2) a centering recessprovided in said end face; (f) brushes mounted on said brush carrierplate for cooperation with and shifting movement with respect to saidcommutator; and (g) a shaft bearing having inner and outer bearingrings; said outer bearing ring being seated in said centering recess ofsaid brush carrier plate and in said bearing recess of said drivehousing.
 2. The assembly as defined in claim 1, wherein said shaftbearing is a sealed roller bearing.
 3. The assembly as defined in claim1, said inner ring being press-fitted on said rotor shaft.
 4. Theassembly as defined in claim 1, wherein said motor housing has a borderdefining said opening; said border including a stepped fitting surfaceengaging liquid tight a periphery of said brush carrier plate.
 5. Theassembly as defined in claim 1, wherein said brush carrier plate isengaged in said motor housing with a press fit; said motor housinghaving, in a region of said opening, a plurality of deformations andsaid brush carrier plate having a plurality of resilient latching hookshooking behind respective said deformations.
 6. The assembly as definedin claim 5, wherein said deformations comprise tabs partially stampedout of the motor housing.
 7. The assembly as defined in claim 1, furthercomprising a labyrinth seal formed in said brush carrier plate withinand circumferentially about said centering recess; said labyrinth sealbeing situated between said shaft bearing and said commutator.
 8. Theassembly as defined in claim 1, further wherein said brush carrier platecarries a sealing lip extending circumferentially about a periphery ofsaid end face of said brush carrier plate.
 9. The assembly as defined inclaim 8, wherein said sealing lip is integral with said brush carrierplate.
 10. The assembly as defined in claim 8, wherein said centeringmeans comprises a centering recess provided in said end face of saidbrush carrier plate; further comprising a plurality of annularprotrusions disposed on said end face of said brush carrier plate; saidannular protrusions constituting sealing rings disposed concentricallyto said centering recess.
 11. The assembly as defined in claim 10,wherein said annular protrusions are integral with said brush carrierplate.
 12. The assembly as defined in claim 1, further wherein saidmotor housing has a flange for attachment to said outer surface of saiddrive housing; said flange surrounding said opening and being bentoutwardly therefrom.